From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38FE1C433EF for ; Thu, 26 May 2022 03:36:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AD3198D0005; Wed, 25 May 2022 23:36:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AAC968D0002; Wed, 25 May 2022 23:36:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 99AB78D0005; Wed, 25 May 2022 23:36:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 8D0FD8D0002 for ; Wed, 25 May 2022 23:36:50 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 62A4B33B25 for ; Thu, 26 May 2022 03:36:50 +0000 (UTC) X-FDA: 79506482580.16.B47B8AB Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf31.hostedemail.com (Postfix) with ESMTP id 89DF820031 for ; Thu, 26 May 2022 03:36:13 +0000 (UTC) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4L7tqz2sp6zjX7b; Thu, 26 May 2022 11:35:43 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 26 May 2022 11:36:44 +0800 Received: from [10.174.179.234] (10.174.179.234) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 26 May 2022 11:36:42 +0800 Message-ID: <87bdb1c6-5803-d9c0-9208-432027ae1d8b@huawei.com> Date: Thu, 26 May 2022 11:36:41 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH -next v4 3/7] arm64: add support for machine check error safe To: Mark Rutland CC: James Morse , Andrew Morton , Thomas Gleixner , "Ingo Molnar" , Borislav Petkov , Robin Murphy , Dave Hansen , "Catalin Marinas" , Will Deacon , "Alexander Viro" , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , , "H . Peter Anvin" , , , , , Kefeng Wang , Xie XiuQi , Guohanjun References: <20220420030418.3189040-1-tongtiangen@huawei.com> <20220420030418.3189040-4-tongtiangen@huawei.com> <46e5954c-a9a8-f4a8-07cc-de42e2753051@huawei.com> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 89DF820031 X-Stat-Signature: 3wc1ohib13piq5x9iuscfgrsy8eimzwr Authentication-Results: imf31.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf31.hostedemail.com: domain of tongtiangen@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=tongtiangen@huawei.com X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1653536173-572640 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 在 2022/5/25 16:30, Mark Rutland 写道: > On Thu, May 19, 2022 at 02:29:54PM +0800, Tong Tiangen wrote: >> >> >> 在 2022/5/13 23:26, Mark Rutland 写道: >>> On Wed, Apr 20, 2022 at 03:04:14AM +0000, Tong Tiangen wrote: >>>> During the processing of arm64 kernel hardware memory errors(do_sea()), if >>>> the errors is consumed in the kernel, the current processing is panic. >>>> However, it is not optimal. >>>> >>>> Take uaccess for example, if the uaccess operation fails due to memory >>>> error, only the user process will be affected, kill the user process >>>> and isolate the user page with hardware memory errors is a better choice. >>> >>> Conceptually, I'm fine with the idea of constraining what we do for a >>> true uaccess, but I don't like the implementation of this at all, and I >>> think we first need to clean up the arm64 extable usage to clearly >>> distinguish a uaccess from another access. >> >> OK,using EX_TYPE_UACCESS and this extable type could be recover, this is >> more reasonable. > > Great. > >> For EX_TYPE_UACCESS_ERR_ZERO, today we use it for kernel accesses in a >> couple of cases, such as >> get_user/futex/__user_cache_maint()/__user_swpX_asm(), > > Those are all user accesses. > > However, __get_kernel_nofault() and __put_kernel_nofault() use > EX_TYPE_UACCESS_ERR_ZERO by way of __{get,put}_mem_asm(), so we'd need to > refactor that code to split the user/kernel cases higher up the callchain. > >> your suggestion is: >> get_user continues to use EX_TYPE_UACCESS_ERR_ZERO and the other cases use >> new type EX_TYPE_FIXUP_ERR_ZERO? > > Yes, that's the rough shape. We could make the latter EX_TYPE_KACCESS_ERR_ZERO > to be clearly analogous to EX_TYPE_UACCESS_ERR_ZERO, and with that I susepct we > could remove EX_TYPE_FIXUP. > > Thanks, > Mark. According to your suggestion, i think the definition is like this: #define EX_TYPE_NONE 0 #define EX_TYPE_FIXUP 1 --> delete #define EX_TYPE_BPF 2 #define EX_TYPE_UACCESS_ERR_ZERO 3 #define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 #define EX_TYPE_UACCESS xx --> add #define EX_TYPE_KACCESS_ERR_ZERO xx --> add [The value defined by the macro here is temporary] There are two points to modify: 1、_get_kernel_nofault() and __put_kernel_nofault() using EX_TYPE_KACCESS_ERR_ZERO, Other positions using EX_TYPE_UACCESS_ERR_ZERO keep unchanged. 2、delete EX_TYPE_FIXUP. There is no doubt about others. As for EX_TYPE_FIXUP, I think it needs to be retained, _cond_extable(EX_TYPE_FIXUP) is still in use in assembler.h. Thanks, Tong. > .